ANSWER Archie, We're sending you some additional information, but installing the heater assembly to the inlet duct, is pretty simple, align the end of the assembly with the inlet duct opening, slip the end into the opening and install and tighten the mounting screws to the mounting bracket. If the inlet duct has been removed, you will need to re mount it to the backside of the rear bulkhead, with the screws, and move on from there. Thanks